Alex Plunkett, left, and Sean Hart, both of Arlington, Va., join hundreds participating in the annual International Pillow Fight Day on April 5. Massive pillow fights broke out on the Mall in Washington and in cities around the world. (Photo by Marvin Joseph/The Washington Post)

Professor Xie Yong works on an art installation of a beaver, which is made out of plastic and around 300,000 needles, in Shenyang, Liaoning province, July 23, 2013. The needles, according to Xie, represent the pain felt by animals when their fur is taken off to produce clothing. (Photo by Reuters/Stringer)